Mesostructural simulation of discontinuous prepreg platelet based carbon fibre sheet moulding compounds informed by X-ray computed tomography

Discontinuous prepreg platelet based carbon fibre sheet moulding compound (CF-SMC) materials offer huge potential for lightweight applications in the automotive industry. The composition of these materials and the flow behaviour during compression moulding result in a complex stochastic mesostructure, which presents a challenge in the modelling of the mechanical behaviour. The objective of the current work is to use the information obtained from multiscale X-ray computed tomography (XCT) scans to generate full-scale three-dimensional finite element models of tensile coupon specimens for the prediction of the elastic modulus. The models incorporate the stochastic distribution and discontinuous nature of the prepreg platelets. Defects such as porosity, resin-rich areas and fibre waviness can be observed by means of XCT. Porosity is found to be below 0.0076 vol.% and thus negligible. An average volume fraction of 6.48 vol.% of interlaminar resin-rich areas is considered in the mesostructural simulations. The predicted values of the tensile modulus are validated by experimental tensile tests on basis of a large series of specimens. The statistical analysis of variance methodology is employed to reach conclusive validation. The inherent stochasticity of prepreg platelet based CF-SMC materials is well captured with the proposed mesostructural simulation approach and the variability in their mechanical properties is accurately predicted.